1. Field
The presently disclosed subject matter relates to surface mount light-emitting devices, and more particularly to side view type and lead frame type surface mount light-emitting devices having high reliability, which is easy to be mounted on a mounting board with high positional accuracy, and which can enjoy a high radiation performance even when the devices emit various color lights including substantially white light having a high light-emitting intensity.
2. Description of the Related Art
Surface mount light-emitting devices are used for semiconductor light-emitting devices such as an LED and the like because the devices may be miniaturized and also may be easy to be mounted directly on a mounting board along with other parts. In the surface mount light-emitting devices, side view type surface mount light-emitting devices, which may emit light in a substantially parallel direction to the mounting board, are frequently used as a light source for LCD back light units in mobile phones, smart phones, digital video cameras, PDAs, etc.
In addition, because it is desired for the side view type semiconductor light-emitting devices to emit various color lights having a high light-emitting intensity in view of the above-described applications being expanded from small size usage to larger size usages such as in general lighting and vehicle lamp lighting, demand has increased for lead frame type surface mount light-emitting devices that can be used for a high light-emitting intensity type apparatus and/or a wide-screen apparatus. Accordingly, side view type and lead frame type surface mount light-emitting devices, which can emit various color lights having a high light-emitting intensity, have been developed.
However, because high light-emitting intensity type devices are generally driven by a large current, their rated wattages and heating values become large, and also the high light-emitting intensity type devices are frequently used under a harsh environment such as high temperature and high humidity and the like, especially when they are used for vehicle lamps, outdoor lighting, etc. Hence, a conventional side view type light-emitting package and a lead frame type light-emitting device using the package, which may improve a radiation performance and the like, are disclosed in Patent Document No. 1 (Japanese Patent Application Laid Open JP2013-219357). FIG. 8 is an enlarged perspective view depicting a conventional side view and lead frame type light-emitting device, which is disclosed in patent document No. 1.
The conventional light-emitting device 100 includes: a package 101 having a cavity 102, an inner side surface 103, an inner bottom surface 104 and an outer bottom surface 105 made from a resin such as an epoxy resin and the like; and a first lead frame 110 having a first mounting surface 110a, a first external electrode 110b, a first electrode end 110c and a first electrode bending portion 110d passing through the package 110, the first mounting surface 110a exposed from the inner bottom surface 104 in the cavity 102 of the package 101, the first external electrode 110b projecting from the package 101, bending along the outer bottom surface 105 of the package 101 via the first electrode bending portion 110d, and extending along the outer bottom surface 105 toward the inner bottom surface 104 of the package 101, the first electrode end 110c being a cutting surface of a multifaceted first lead frame to improve a productivity of the device 100.
In addition, the conventional light-emitting device 100 also include: a second lead frame 120 having a second mounting surface 120a, a second external electrode 120b, a second electrode end 120c and a second electrode bending portion 120d passing through the package 101, the second mounting surface 120a exposed from the inner bottom surface 104 in the cavity 102 of the package 101, the second external electrode 120b projecting from the package 101, bending along the outer bottom surface 105 of the package 101 via the second electrode bending portion 120d, and extending along the outer bottom surface 105 toward the inner bottom surface 104 of the package 101, the second electrode end 120c being cutting surfaces of a multifaceted second lead frame to improve a productivity of the device 100; semiconductor light-emitting chips 130 and 131 each having a bottom electrode and a top electrode mounted on the first mounting surface 110a of the first lead frame 110, the bottom electrodes thereof being electrically connected to the first lead frame 110, and each of the top electrodes thereof being electrically connected to the second mounting surface 120a of the second lead frame 120 via bonding wires 140 and 141, respectively; and a zener diode 132 having a bottom electrode and a top electrode mounted on the second mounting surface 120a of the second lead frame 120, the bottom electrode thereof being electrically connected to the second lead frame 110, and the top electrodes thereof being electrically connected to the first mounting surface 110a of the first lead frame 110 via a bonding wire 142.
When manufacturing the conventional light-emitting device 100 of the side view and lead frame type having such a structure, an insert molding method may be employed by inserting the multiple first lead frame and the multiple second lead frame into a mold tool, which molds a multiple package, so that the light-emitting device 100 integrates the first and the second lead frames 110 and 120 into the package 101 to improve the productivity thereof. Then, each of the first and the second lead frames 110 and 120 may be cut and may be bended in the above-described shape. Thereby, for example, 100 pieces of the package 101 integrating the first and the second lead frames 110 and 120 may be made at once.
FIGS. 9a and 9b are a right side cross-sectional view and a left side cross-sectional view depicting the light-emitting device 100 shown in FIG. 8 mounted on a mounting board 200, in which a first conductor pattern 201 and a second conductor pattern 202 are formed on the mounting board 200 to mount the device 100, respectively. The conventional light-emitting device 100 may be mounted on the mounting board 200 by soldering between the first conductor pattern 201 of the mounting board 200 and the first external electrode 110b of the first lead frame 110 and between the second conductor pattern 202 of the mounting board 200 and the second external electrode 120b of the second lead frame 120.
In this case, each soldering surface of the first external electrode 110b of the first lead frame 110 and the second external electrode 120b of the second lead frame 120 may be coated with thin coating to improve each of soldering intensities between the first conductor pattern 201 of the mounting board 200 and the first external electrode 110b of the first lead frame 110 and between the second conductor pattern 202 of the mounting board 200 and the second external electrode 120b of the second lead frame 120. However, it may be almost impossible for each of the first electrode end 110c of the first lead frame 110 and the second electrode end 120c of the second lead frame 120 to coat the thin coating, because each of the first electrode end 110c and the second electrode end 120c may become the cut surface of the multiple first lead frame and the multiple second lead frame, respectively.
Accordingly, a soldering fillet may not be formed at each of the first electrode end 110c of the first lead frame 110 and the second electrode end 120c of the second lead frame 120, although soldering fillets 150 and 151 may be formed at each of the first electrode bending portion 110d of the first lead frame 110 and the second electrode bending portion 120d of the second lead frame 120 as shown in FIG. 9b and FIG. 9a, respectively. Therefore, a positional accuracy of the conventional light-emitting device 100 with reference to the mounting board 200 may be subject to a degradation due to a difference between amounts of a first solder 203 melted between the first conductor pattern 201 of the mounting board 200 and the first external electrode 110b of the first lead frame 110 and a second solder 204 melted between the second conductor pattern 202 of the mounting board 200 and the second external electrode 120b of the second lead frame 120, etc.
In addition, a radiation performance of the conventional light-emitting device 100 may also degrade because of a difference between the soldering intensities of the first and the second solders 203 and 204. The degradations may cause a decrease of a reliability of the conventional light-emitting device 100 in operation on the mounting board 200, and also may cause a decrease of a light-emitting-directional accuracy of light emitted from the conventional light-emitting device 100.
The above-referenced Patent Document and additional Patent Documents are listed below, and are hereby incorporated with their English abstracts in their entireties.    1. Patent Document No. 1: Japanese Patent Application Laid Open JP2013-219357    2. Patent Document No. 2: U.S. Pat. No. 8,860,047    3. Patent Document No. 3: U.S. Pat. No. 8,860,061
The disclosed subject matter has been devised to consider the above and other problems and characteristics. Thus, embodiments of the disclosed subject matter can include side view and lead frame type surface mount light-emitting devices, which can be easily mounted on a mounting board with high positional accuracy, and which can emit various color lights including substantially white light having a high light-emitting intensity in a substantially parallel direction to the mounting board. In addition, the embodiments of the disclosed subject matter can also include reliable side view and lead frame type surface mount light-emitting devices have high radiation performance even when emitting the various color lights having the high light-emitting intensity.